Material transfer system stoppage warning device



Oct. 9, 1962 H. J. BURROWS ETAL 3,05

MATERIAL TRANSFER SYSTEM STOPPAGE WARNING DEVICE Filed March 1'7, 1958 INVENTORS HARRY J. BURROWS 8| MICHAEL M. BLONCHEK .AH TORNEY Unite This invention relates to a novel warning device to provide an automatic signal when a stoppage has occurred in a solid material handling system.

More particularly, the warning device of this invention may be used in association with continuous feed systerns whereby a relatively coarse material such as coal, metallic or non-metallic ores, gravel, road slag, and the like is transported by the force of gravity from an elevated storage bin through a chute to the point of use or place of further treatment. This warning device is particularly well suited for use with a continuous coal feeding system for a steam boiler furnace such as in association with the coal bin and chute adapted to feed a chain grate stoker or spreader stoker on a boiler furnace.

One serious operational problem attendant to such a coal stoker system is a stoppage of coal somewhere in the bin or chute so as to interrupt the supply of coal to the moving chain or grate and consequently causing the fire within the furnace to either burn itself out or to fall to such a level so that the steam pressures generated by the furnace may be critically impaired. Should the fire burn itself out, a long and costly delay may be encountered before the steam pressures can be returned to necessary levels for the normal needs of a dependent plant. This is a particularly grave problem in plants Where the steam is employed in the operation of continuous processes, such as a petroleum refinery.

Other than for a lack of inventory, these stoppages in a continuous feed system are due generally to some phenomenon such as bridging where several particles wedge together in a manner to seed a blockage across the gravity feed bin or in the chute of the feed system. Normally, such stoppages, if noticed in suflicient time, may be readily corrected in conventional ways by attending operators before 'any serious consequences in operation are experienced.

It is therefore the object of this invention to provide an alarm indicating means which will automatically warn operators of a feed stoppage from a gravity feed bin which supplies feed material to an endless conveyor. It is the particular object of this invention to provide an alarm indicating means to signal the stoppage of coal in a continuous coal feeding system to a boiler furnace comprising a gravity feed bin and chute and a moving chain conveyor.

In accordance with the invention, a rigid cylindrical shaft is inserted in a flowing stream of coarse material States Patent v at some convenient point in a continuous feed system.

The shaft may be placed directly in the gravity feed bin or in the chute leading from the bin to the conveyor of the feed system. It is more convenient, however, to locate the shaft below the chute in a horizontal plane by means of an appropriate journal so that the shaft is immediately above the upper surface of the conveyor at a position where its innermost end is a short distance beyond the outside lip of the chute. The shaft is provided with a boss at the end which is inserted in the flowing stream, and the force exerted by the moving mass of coarse material in contact with it from the gravity feed bin and chute is sutlicient to hold the shaft in the stream as against an opposing force at the other end of the shaft which may be provided by a biased spring or other means. If the flow of material within the chute is in- 3,058,102 Patented Oct 9, 1 962 terrupted for any reason whereby little or no coarse material is in contact with the boss on the end of the shaft, the biased spring forces the shaft to move in an axial direction whereby an electrical switch is tripped by the outer end of the shaft. This switch actuates a sensible signal to attract the attention of the operators. The signal may be any device, such as a horn or light, which is positioned at a convenient location to be readily noticed by the operators, such as a position in the aisle near the feeding system or at a centrally located control board. The operators may then take whatever steps that are necessary to correct the stoppage and once normal flow has been resumed, the shaft may be again inserted in its original position in the flow of feed and the alarm closed to its off position. v

A more complete understanding of the invention will be gained from the following description, taken together with the patent drawing, which is a fragmentary sectional and elevational view of the best mode contemplated at present for carrying out the invention.

Referring now to the drawing, the invention is employed in connection with a chain grate stoker 10 which includes a coal bin 11, a coal chute 12, and chain grate conveyor 13 providing a continuous feed system of coal to the boiler furnace 14. Chain grate conveyor 13 is driven continuously at a slow rate of speed through the furnace 14 by means of an electrical motor not shown in the drawing. The alarm indicating means of the invention is shown as when in operational position. The shaft 15 is supported in a substantially horizontal position by journal 16 so as to be freely movable toward and away from the coal chute 12. The journal 16 is secured in the position shown by means of the bracket 17 which is attached to the lower housing 18 of the chain grate stoker 10. Shaft 15 has at its inner end a boss 19 which rests upon the upper surface of the endless chain grate conveyor 13 in the manner shown. Shaft 15 is inserted in the flowing stream of coarse coal to a position such as at 20, which biases the coil spring 21 between the header 22, which is mounted on the outer end of shaft 15, and the journal 16. The shaft 15 is held in this position against the resistance of the compressed spring 21 by the mass of coal 23 in contact with the boss 19 from chute 12. While the apparatus is in this operational position, the lever 24 of switch 25 is in the off position and the electrical circuit to the indicating bulb 26 is open.

The operation of the apparatus will now be described. When coal fails to remain in contact with the boss 19, such as by an exhausted inventory in bin 11 or by a coal stoppage due to bridging of the coal particles in either the bin 11 or chute 12, the biased spring 21 forces the shaft 15 outward through journal 16. This movement of shaft 15 causes the header 22 to trip lever 24, moving the switch 25 to the on position. The electrical circuit is thereby closed, lighting the indicating bulb 26 which alerts the attending operators of the coal stoppage to the chain grate conveyor 13. After this stoppage has been corrected and flow of the coal resumes, the shaft 15 may be inserted in its original position, such as at position 20.

It will be obvious that variations in the structure and mode of operation may be made without departing from the inventive concept herein disclosed, and we intend all of the same to be within our invention as are included within the scope of the following claims.

We claim:

1. In combination with a continuously operating system for handling particulate material, comprising a rotatable endless conveyor and a superposed gravity feed hopper;

(a) an indicator means (b) a device for activating said indicator means in response to a stoppage of particulate material flow from the feed hopper to the endless conveyor, said device comprising,

(1) an oscillatable shaft having a near end interposing the hopper and conveyor and a distal end disposed laterally beyond the limits of the hopper and conveyor,

(2) means mounting said shaft for oscillative movement along a path of travel in a plane perpendicular to the plane in which lies the axis of rotation of said endless conveyor,

(3) means connected to said shafts near end responsive to the force of particulate material flowing therepast, for urging the shaft in a first direction,

(4) counter-force means connected to said shafts distal end for urging the shaft in a second direction opposite to said first direction,

(5) switch means for said indicator means, posi- 20 tioned in the path of travel of the distal end of said shaft,

whereby when the force of flowing particulate material operating on the near end of the shaft is reduced below a predetermined value, the shaft, under the influence of said counter-force means, moves in said second direction thereby causing the distal end of the shaft to contact the switch means, thus activating the indicator means.

2. The device of claim 1 wherein the counter-force means is a spring.

3. The device of claim 1 wherein the indicator means is an electric lamp.

References Cited in the file of this patent UNITED STATES PATENTS Donner Sept. 3, Donner Sept. 3, Rice May 7, Tyden Oct. 3, Voliazzo et al June 10, Ellerbeck Aug. 5, Parisi Oct. 16, Whittle Oct. 9, Reid Nov. 27, 

